package ms.core.common;

import java.nio.charset.Charset;
import java.util.Locale;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * An <a href="http://tools.ietf.org/html/rfc2045">RFC 2045</a> Media Type,
 * appropriate to describe the content type of an HTTP request or response body.
 */
public final class MediaType {
	public static enum ContentType {appJson, appText, appXml, formEncoded, formMultiPart, txtHtml, txtPlain, txtXml};

	private static final String TOKEN = "([a-zA-Z0-9-!#$%&'*+.^_`{|}~]+)";
	private static final String QUOTED = "\"([^\"]*)\"";
	private static final Pattern TYPE_SUBTYPE = Pattern.compile(TOKEN + "/" + TOKEN);
	private static final Pattern PARAMETER = Pattern.compile(";\\s*(?:" + TOKEN + "=(?:" + TOKEN + "|" + QUOTED + "))?");

	private final String mediaType;
	private final String type;
	private final String subtype;
	private final String charset;
	private ContentType contentType;

	private MediaType(String mediaType, String type, String subtype, String charset) {
		this.mediaType = mediaType;
		this.type = type;
		this.subtype = subtype;
		this.charset = charset;
		this.contentType = null;

		if ("multipart".equals(type)) 
			contentType = ContentType.formMultiPart;
		
		if ("application".equals(type) && subtype!=null) {
			if (subtype.contains("x-www-form-urlencoded")) contentType = ContentType.formEncoded;
			if (subtype.contains("json")) contentType = ContentType.appJson;
			if (subtype.contains("text")) contentType = ContentType.appText;
			if (subtype.contains("xml")) contentType = ContentType.appXml;
		}

		if ("text".equals(type) && subtype!=null) {
			if (subtype.contains("html")) contentType = ContentType.txtHtml;
			if (subtype.contains("plain")) contentType = ContentType.txtPlain;
			if (subtype.contains("xml")) contentType = ContentType.txtXml;
		}
	}

	/**
	 * Returns a media type for {@code string}, or null if {@code string} is not a well-formed media type.
	 */
	public static MediaType parse(String string) {
		Matcher typeSubtype = TYPE_SUBTYPE.matcher(string);
		if (!typeSubtype.lookingAt())
			return null;

		String type = typeSubtype.group(1).toLowerCase(Locale.US);
		String subtype = typeSubtype.group(2).toLowerCase(Locale.US);

		String charset = null;
		Matcher parameter = PARAMETER.matcher(string);
		for (int s = typeSubtype.end(); s < string.length(); s = parameter.end()) {
			parameter.region(s, string.length());
			if (!parameter.lookingAt())
				return null; // This is not a well-formed media type.

			String name = parameter.group(1);
			if (name == null || !name.equalsIgnoreCase("charset"))
				continue;

			String charsetParameter = parameter.group(2) != null ? 
					parameter.group(2) : // Value is a token.
					parameter.group(3);  // Value is a quoted string.
			if (charset != null && !charsetParameter.equalsIgnoreCase(charset)) {
				throw new IllegalArgumentException("Multiple different charsets: " + string);
			}
			charset = charsetParameter;
		}

		return new MediaType(string, type, subtype, charset);
	}

	/**
	 * Returns the high-level media type, such as "text", "image", "audio", "video" or "application".
	 */
	public String type() {
		return type;
	}

	/**
	 * Returns a specific media subtype, such as "plain" or "png", "mpeg", "mp4" or "xml".
	 */
	public String subtype() {
		return subtype;
	}

	/**
	 * Returns the charset of this media type, or null if this media type doesn't specify a charset.
	 */
	public Charset charset() {
		return charset != null ? Charset.forName(charset) : null;
	}

	/**
	 * Returns the charset of this media type, or {@code defaultValue} if this media type doesn't specify a charset.
	 */
	public Charset charset(Charset defaultValue) {
		return charset != null ? Charset.forName(charset) : defaultValue;
	}
	
	public ContentType contentType() {
		return contentType;
	}

	/**
	 * Returns the encoded media type, like "text/plain; charset=utf-8", appropriate for use in a Content-Type header.
	 */
	@Override
	public String toString() {
		return mediaType;
	}

	@Override
	public boolean equals(Object o) {
		return o instanceof MediaType && ((MediaType) o).mediaType.equals(mediaType);
	}

	@Override
	public int hashCode() {
		return mediaType.hashCode();
	}

	public static void main(String[] args) {
		String contentType = "application/vnd.spCampaign.v3+json";
		MediaType mt = MediaType.parse(contentType);
		System.out.println(mt.type + "  " + mt.subtype + "  "+ (mt.contentType==ContentType.appJson));
	}
}